226 Biologie. — Morphologie etc. 



even in this tribe, there are very few records of irritable species. 

 Very few authors have recorded the exact type of irritability and 

 none has recorded the degree of irritability. The present writer has 

 examined 233 species and varieties, and this investigation has yielded 

 149 records of irritability, mostly new. Irritability was found in 64 

 per Cent of the species and varieties examined, and in all the tribes 

 of the family except the Eupatorieae and the Vernonieae. In the 

 list of cases, the degree and type of irritability observed are 

 recorded. Notes on special, interesting cases, such as the explosive 

 irritability in the Mutisieae, and the peculiar, slow movement in the 

 Cichorieae, are appended. The interest of the aulhor's work is 

 enhanced by the fact that he has observed irritability in the case 

 of certain extremely common plants — such as Bellis perennis and 

 Taraxacum officinale — on which this phenomenon had hitherto 

 been entirely overlooked by botanists. 



Agnes Arber (Cambridge). 



Swynnerton, C. F. M„ Short Cuts by Birds to Nectaries. 

 (Journ. Linn. Soc. Bot. Vol. XLIII. p. 381—416. 2 pl. 1916.) 



Extensive observations on this subject have been made by the 

 writer in the neighbourhood of the Chirinda Forest in the Metsetter 

 district of Southern Rhodesia. The results are described in 

 detail and lists of all the birds and plants in question are included. 

 The main points may be summarised as follows: 



Not only mainly ornithophilous flowers, but a number of 

 essentially entomophilous flowers were visited by sunbirds. Not 

 only sunbirds, but many other birds as well, visiting certain flowers 

 freely for their honey were probably of use to them for cross- 

 fertilization, Certain birds, and sorae individuals more than others, 

 apparently disliked something in connection with the natural 

 opening — possibly being besprinkled with pollen — and tended 

 always to enter flowers by breaches made by themselves or their 

 predecessors. Other birds tended, contrarywise, to enter the flowers 

 by their natural openings and so to be of use to them for cross- 

 fertilization, excepting in the case of individual flowers that 

 happened, through inconvenience in their aim on the bird's position, 

 etc., to offer some difficulty. If these were insufficiently protected 

 as well, they were often either pierced, or the openings already 

 made in them by the more indiscriminating birds were utilized. 

 Protection took several forms — thin, pliable pedicels, massing of 

 the flower for mutual protection (a possible factor in the evolution 

 of the capitulum), thickening of parts, and so on. Insects as well 

 as birds noted and utilized the breaches made by the latter, and so 

 probably in large part acted to counteract the bird's discriminative 

 influence. In most cases the eliminative effect, if any, of the damage 

 was not traced. In two instances it was (for individuals). immediate 

 and clear, flowers of a certain type being bodily removed. 



Agnes Arber (Cambridge). 



Woolery, R., Meiotic Divisions in the Microspore Mother- 

 cells of Smilacivia racemosa (L.) Desf. (Ann. Bot. XXIX. p. 471—482, 

 1 pl. and 1 textfig. 1915.) 



The work recorded in this paper was undertaken primarily in 

 Order to test the results of Lawson, A. A. (The Phase of the 



